Autonomic dysfunction in systemic sclerosis: time and frequency domain 24 hour heart rate variability analysis.

To evaluate the autonomic nervous control of the heart in patients with systemic sclerosis (SSc), spontaneous heart rate variability was investigated by means of time-domain and spectrum analysis of 24 h ECG ambulatory recordings in 30 SSc patients (four males, aged 45.2 +/- 9 yr, mean +/- S.D., range 27-60) and 30 age-matched healthy subjects. A significantly higher heart rate (P < 0.01) and lower circadian and spectral indices of heart rate variability (P < 0.01) were observed in SSc patients, compared with controls. A predictive value of age (P = 0.002), tachycardia (P = 0.002), circadian heart rate variability (P = 0.0025) and spectral power values (P = 0.005) for patient mortality was found. Moreover, the relative risk of death was higher (P = 0.05) in older subjects with circulating anti-Scl70. These abnormalities, detectable by a feasible, non-invasive diagnostic approach, indicate the presence of autonomic cardiac neuropathy in SSc patients.